@Wreck, over at Caps-a-holic the winner is the Blu ray Sapphire series because of less use of DNR.Pretty sure it's all derieved from the same HD transfer worldwide. The difference would be because it's been released by both Fox and paramount that the encoding might be different.
by all accounts, the US BD has the slight edge because the video bitrate is slightly higher. If it's audio your after, best bet would be to look at the Asian releases and quite a majority of titles have higher spec audio mixes (96Khz upsampled Dolby TrueHD for example)
The first couple of Sapphire Editions were Gladiator and Saving Private Ryan. Gladiator had to get a rerelease since the 1st transfer was bad with disappearing Arrows and flames, among other Video problems.I cant remember what title it was, but I recall one of the sapphire series title having to be re done. Was Gladiator ever sapphire series? I remember that one getting remastered.